1. Field of the Invention
The present invention relates to a radio equipment, and more particularly to scanning receiver systems in such radio equipment.
2. Related Art
Radio communication systems for performing radio communication with a partner by using a predetermined channel selected from a plurality of carrier frequency channels are widely used.
Heretofore, in a radio communication system of such a type, a plurality of carrier frequency channels are provided in one-to-one correspondence with a plurality of memories which are arranged in one bank or arranged separately in a plurality of banks so that channel scanning is carried out in the order of the channel numbers in each bank.
Conventionally, therefore, the channel scanning speed is determined on the basis of PLL lock-up time (the time required for settling down a PLL unit to an altered frequency) and squelch response time (the time required for detecting a reception signal after alteration of the frequency). Particularly in the case where the change in frequency is relatively large, a long PLL lock-up time is required. In a radio communication system of such a type, it is therefore desirable that the PLL lock-up time is shortened as much as possible at the time of channel scanning, in order to maximize the channel scanning speed.